Tap extractor with slidably adjustable fingers



Feb. 26, 1957 G. J. MILLER I TAP EXTRACTOR WITH SLIDABLY ADJUSTABLEFINGERS Filed May 27, 1955 IN V EN TOR.

GEO/V65 J MILLER. BY

HTTOPNEX United States Patent TAP EXTRACTOR WITH SLIDABLY ADJUSTABLEFINGERS George J. Miller, Windsor, Conn., assignor to The WaltonCompany, Hartford, Conn. Application May 27, 1955, Serial No. 511,581 6Claims, (Gist-9o This invention relates to a tap extractor and moreparticularly to a device for extracting broken taps from threaded holesby rotating" such taps within the holes.

It is commonly known that, heretofore, extractors for broken taps havebeen used which included a set of fingers that were insertable into theflutes of the broken tap for rotating it to extract it from the hole. Insuch previously known extractors, the fingers were interconnected insuch a manner that they had to be inserted into their respective flutesfor the same distance and, in cases where one or more of the flutes wereclogged with chips or the like, the insertion of all of the fingers waslimited to the distance permitted by the clogged flute and, in some ofsuch cases, the clogged Condition of the flutes resulted in aninsufiicient connection between the extractor and the broken tap.

In other devices, such as in the co-pending application of Kenneth W.Weeks, Serial No. 484,539, filed Janumy 27, 1955, the extractor fingersare movable independently of each other but a separate operation isrequired to secure the fingers in their operative position after theyhave been inserted into their respective flutes, of a broken tap.

It is an object of this invention, therefore, to provide an extractorfor broken taps in which each of the plui'ality of tap engaging fingersmay be extended from a holder and inserted into a flute of the brokentap independently of the other fingers, by merely moving each fingel onthe holder and without requiring a separate operation for securing thefingers to the holder in operative positions.

A further object of this invention is to provide such an extractor whichis highly eflicient in its operation and which may be economicallyproduced by reason of its simplicity of construction.

A still further object is the provision of an extractor for broken tapshaving a plurality of tap engaging fingers which are constantly heldconnected to a holder therefor and which may be moved in said holderindependently of each other with only the simple operation of movingeach finger to extend its free end from the holder and into a respectiveflute in a broken tap until it has entered said flute for the desireddistance or until movement of said free end of the finger into the fluteis interrupted by a clogged or similar condition of said flute.

Further objects and advantages of this invention will be more clearlyunderstood from the following description and from the accompanyingdrawings in which:

Fig. 1 is a side view of an extractor for broken taps embodying thepresent invention.

Fig. 2 is a top end view thereof.

Fig. 3 is a bottom end view.

Fig. 4 is a view in central vertical section on line 44 of Fig. 3.. r

Fig. 5 is a sectional end view on line 5-5 of Fig. 4.

As shown in the drawings, my improved extractor includes a holder 5having a squared head 6 and a plurality 2,782,667 Patented Feb. 26, 1957of elongated grooves 7 running longitudinally in its outer surface.

Each of said grooves is open at the bottom end of the holder 5 and hasslidably mounted therein a finger 8 having a straight end portion. Ifdesired, the said fingers may be provided with an offset grip portion10. The number of said grooves and fingers in a holder is preferablymade to correspond to the number of flutes in a tap for which the toolis intended and the diameter of the holder 5 is made to substantiallyconform with the root diameter of said tap.

The fingers 8 are retained in adjusted position upon the holder 5 and intheir respective grooves 7 by means of a retaining sleeve 11 which isslidable over said holder and the fingers 8 therein and has a bushing12, of rubber or other suitable resilient material, which is containedwithin an annular groove 13 in the wall of the axial bore of said sleeve11 and extends for a portion of the length of said bore.

In the preferred construction of my improved extractor for broken taps,the outside surfaces of the fingers 8 are contoured to conform with thecircular contour of the holder 5 and, when located in their respectivegrooves in said holder, the outer surfaces of said fingers are disposedupon a diameter which is slightly less than the diameter of the holder5. The sleeve 11 has a bore of a diameter to slidably receive the holderand fingers and allow a slight clearance between the outer surfaces ofthe fingers and the surface of the bore to provide a tolerance forslight variations in the diameter at the outside surfaces of the fingerswhich will prevent binding of such fingers between the bottoms of thegrooves and the wall of the bore in the sleeve and facilitate themanufacture of such tap extractors on a volume basis at a minimum cost.

The resilient bushing 12 provided by the present invention isconstructed with an inside diameter that is nor mally slightly less thanthe diameter at the outside surfaces of said fingers and, when thesleeve 11 is mounted over the holder and fingers, the said bushing willbecome compressed between the outer surfaces of the fingers and holderand the bottom surface of the annular groove 13 and thereby firmly forcethe fingers 3 against the bottoms of the respective grooves 7 while alsoengaging with the outer surfaces of the holder 5 and frictionallyretaining the said fingers in their adjusted positions relatively to theholder 5. It will be understood that the resiliency of the bushing 12will cause portions of said bushing to reach into the grooves 7 andengage the outer surfaces of the respective fingers therein while otherport-ions of said bushing are in engagement with the outer surfaces ofthe holder.

In the use of my improved extractor for broken taps, the end of theholder 5 is first placed against the end of the broken tap which is tobe extracted. In cases where the end of the broken tap is inside of ahole, the said holder is inserted into the hole until it strikes the endof the tap. Each of the fingers is then separately pro jected from theholder and inserted into a flute of the said broken tap as far as itwill enter. The sleeve 11 is then slid forwardly upon the holder, untilit is positioned as close to the hole and as near to the end of thebroken tap as possible, and the operation of attaching my improvedextractor to the said broken tap is completed.

It will be noted 'from the illustration in Fig. 4 that the resilientbushing 12 extends only for a portion of the length of the bore in thesleeve 11 and that it is located adjacent the top end of the sleeve. Theportion of the bore which is adjacent to the bottom end of said sleevehas a rigid wall which provides a rigid backing for each of the fingers8 to prevent outward movement of the fingers relatively to the holderwhen side pressure is applied to said fingers during the rotation of thetool in the process of extracting a broken tan.

I claim:

- 1. An extractor for broken taps including a holder having a pluralityof grooves disposed longitudinally-in its outer surface and extending'toa free end thereof, a separate elongated finger member slidablymounted'in each of said grooves and having an end portion adapted to beextended beyond the said free end of the holder, a sleeve surroundingsaid fingers and holder, and resilient means combined with said sleevefor independently retaining each of the fingers in position within itsrespec tive groove in said holder.

2. An extractor for broken taps including a holder having a plurality oflongitudinally disposed grooves opening at an end thereof, a separateelongated'finger member slidably contained in each of said grooves andhaving an end portion adapted to be extended beyond the end of theholder, a sleeve slidable over said holder and fingers, and a resilientbushing in said sleeve frictionally engaging said fingers and therebyindependently retaining each finger in adjusted position in itsrespective groove and relatively to the holder.

3. An extractor for broken taps including a holder having a plurality ofgrooves disposed longitudinally in its outer surface and extending to anend thereof, a plurality of elongated fingers slidably mounted in saidgrooves and having free end portions extendable from the said end of theholder, the outer surfaces of said fingers when located in said groovesbeing disposed upon a diameter which is slightly less than the diameterof the holder, a sleeve slidable over said holder and fingers, and aresilient bushing compressed between said holder and fingers and saidsleeve and normally having an inner diameter which is slightly less thansaid diameter at the outer surfaces of the fingers.

4. An extractor for broken taps including a holder having a plurality ofelongated grooves extending longitudinally in its outer surface andextending to an end thereof, a separate elongated finger slidablymounted in each of said grooves and having a free end'portion extendablefrom said end of the holder, each of said fingers when contained in itsrespective groove having its outer surfaces on a diameter which isslightly less than the diameter of the holder, a sleeve slidably mountedupon said holder and over said fingers, said sleeve having a boreslidably receiving the holder and of a diameter providing a clearancebetween the inner surface of said sleeve and the outer surfaces of thefingers whereby the said sleeve is prevented from interfering with thesliding movement of the fingers in their respective grooves, and abushing of a resilient material contained in said sleeve and extendingalong a portion of the length of the said bore, said bushing have aninside diameter which is normally less than the diameter at the outersurfaces of the fingers and being compressed between said holder andfingers and the inner wall of the sleeve for retaining the said holder,fingers and sleeve in adjusted position relatively to each other. v 5.An extractor for broken taps including a holder having a top end, abottom end and a plurality of elongated grooves in its outer surfaceopening at the bottom end of said holder, elongated fingers contained insaid grooves and each adapted to be positioned for extending an endportion thereof beyond said bottom end of the holder independently ofthe other fingers, 'a'sleeve slidably mounted over said holder andfingers and having a portion directly engageable by said fingers toprevent radial movement of the fingers relatively to the holder, and aresilient bushing in another portion of said sleeve engaging the saidholder and fingers and yieldingly retaining them in adjusted positionrelatively to each other. 6. An extractor for broken taps including aholder having a plurality of elongated grooves in itsouter surfaceextending to a free end thereof, a separate elongated finger memberslidably contained in each of said grooves and having an end portionadapted to be extended to different distances from the said free end ofthe holder,.a sleeve slidable over said holder and fingers, and havingan annular groove in its inner surface, and a resilient bushingcontained in said annular groove and engageable with said holder andfingers for frictionallyretaining the fingers against longitudinalmovement in their respective grooves. I I

References Cited in the file of this patent UNITED STATES PATENTS CantinDec. 14,

